Open Root Server Network (ORSN) was a network of Domain Name System root nameservers for the Internet. ORSN DNS root zone information was kept in synchronization with the "official" Domain Name System root nameservers coordinated by ICANN. The networks were 100% compatible, though ORSN was operated independently. The ORSN servers were primarily placed in Europe. ORSN is also used by public name servers, providing Domain Name System access freely for everyone, without any limitation until the project closed in May 2019.

ORSN was primarily started to reduce the over-dependence of Internet users on the United States and Department of Commerce/IANA/ICANN/VeriSign, limit the control over the Internet that this gives, while ensuring that domain names remain unambiguous. And to avoid the technical possibility of global "Internet shutdown" by one party.They also expect their network to make domain name resolutions faster for everyone.

Markus Grundmann, Germany is the founder of ORSN, and author of ORSN distributed system management and monitoring software solution.

Paul Vixie, the main designer of BIND, the UNIX de facto standard DNS server, is a high-profile proponent of the ORSN.Paul Vixie is member of Security and Stability Advisory Committee of ICANN, he served on the Board of Trustees of the American Registry for Internet Numbers (ARIN) from 2005 to 2013, also as ARIN chairman in 2009 and 2010.

ORSN has 2 operating modes: